Parents would like to think their teenage sons are spending the summer reviewing calculus. Unfortunately, at least a few of them may be manufacturing homemade blowguns, with unexpectedly painful results.

Doctors at Nationwide Children's Hospital in Columbus, Ohio, were puzzled when a 15-year-old boy showed up in the emergency room coughing and wheezing. The youth said the cough started three hours earlier, while he was playing in his room with siblings.

An X-ray showed something long, steely and needle-like in the boy's windpipe.

On further questioning, the boy admitted to having built a blowgun, using instructions he found on the Internet. But the project came to grief when the boy put the blowgun to his lips, then inhaled.

That meant a trip to the operating room, where doctors were able to remove the metal dart using a tube called a bronchoscope. No long term harm done, except perhaps to the young maker's pride.

An odd one-off accident, you might say. But no.

Over the next three months in 2011, the same hospital had two more teenage boys show up coughing. They, too, eventually confessed to inhaling blowgun darts. Those lads, ages 14 and 15, were also treated and recovered.

Emergency room doctors should be aware of the Internet blowgun issue, the study authors say, and think about ordering an X-ray for an adolescent male with sudden coughing and wheezing.

Teenage girls have their own issues with inhaling foreign objects, the report says, but in those cases the foreign object is likely a pin used to secure a turban or headscarf. You're fixing your scarf, you hold the pin in your mouth, you talk to a friend and oops.

Unfortunately some of those girls have had to have throat surgery to remove pins that got lodged sideways.

We wrote earlier this summer about adolescent boys injuring themselves and others with homemade bombs made with soda bottles and household chemicals. Those bombs are also called MacGyver bombs, after the intrepid 1980s TV hero MacGyver.

And wouldn't you know it, a quick Google search finds MacGyver making a blowgun out of a reed, loading it with a dart dipped in sap from a poisonous shrub.

"In order for me to knock him out I'm going to have to hit him just right — right in the neck," MacGyver says.

There's no question that he's going to get that right. Down goes the bad guy.